Motor snap switch



Oct. 2, 1928.

H. G. BAXTER MOTOR SNAP SWITCH Filed March l, 1925 mvENToR a Ham/dBax/er TTORNEY Patented Oct. r2, 1928.

UNITED STATES PATENT OFFICE.

HAROLD G, BAXTER, F BALDWIN, NEW YORK, ASSIGNOR T0 WESTINGHOVUSE ELEC-TRIO @c MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

MOTOR SNAP SWITCH. v

Application filed March 1,

My invention relates to snap switches and more particularly to startingswitches for small motors.

One object of my invention is to provide a snap switch which is composedof feW parts and is simple in construction.

An object of my invention is to provide a snap switch in which a shaftor crank member moves in the same direction for both making and breakingan electrical Contact upon the occurrence of overload conditions.

It is a further object of my invention to provide a snap switch forcontrolling the several circuits employed in starting a singlephaseinduction motor.

It is also an object of my invention to p'rovide a snap switch with atrip-free handle for automatic release from overloads Without theremoval of the operators hand from the handle.

Figure 1 is a diagrammatic illustration of apparatus and circuitsembodying my invention.

Fig. 2 is a plan view of a snap switch embodying my invention.

Fig. 3 is a longitudinal sectional view thereof.

Fig. 4 is a sectional view taken along the line IV-IV of Fig. 3.

Figs. 5, 6 and 7 are diagrammatic illus* trat-ions of the Off, Startingand Running positions of the switch, respectively'.

In Vthe preferred embodiment of my invention, an electrical device 1,such as a single-phase motor, is connected, by an electrical circuit 2.to any suitable source of electrical energy, through a switch 3,embodying my invention.

The switch 3 is of the snap type and comprises a base member 4, ofsuitable insulatingr material, provided With a cover or casing 5,

` preferably of cylindrical form. A turn-button 6, is attached to shaft7 which has an offset portion or crank 8 intermediate its ends. A pairof bifurcated arms 9 and1'1 are mounted on the shaft 7 to straddle thecrank portion 8. A spring 12 connects the crank portion 8 to the arm 11.

Secured to the outer end of arm 9 is an insulated member 13 of anysuitable material, such as micarta material, which carries a contactmember 14 constituting a shuntswitch, and Contact members 15 and 16 con-Stituting a starting switch, that are adapted 1923. vSerial No. 622,052.

to engage fixed contact members 17, 18 and "ff 19, respectively. i

In Ffg. 2, an insulated member 21 is shown secured to the outer end ofthe arm 11. Member 21 carries an. extension 22, having legends such asOnand Off inscribed thereon to co-operate with an opening 23 in the cover5. Member 21 also carries-contact members 24 and 25 constituting-arunning switch Which cooperate With the stationary contacts 26 and 27,respectively.

A spring 28 connects the arms 9 and 11. A balanced latch 29, controlledby a spring 30, is adapted to extend through an opening in arm 9 tosecure the arm, in a manner to be hereinafter described. The latch 29 iscontrolled by a lever 31 actuated by the piston 32 of a dash pot 33.

A. ratchetvvheel 34 is mounted on a sleeve 45 that constitutes anextension of the handle 6. Another ratchet Wheel 35 is secured to theshaft 7 near its outer end for co-operation With a paWl 35a on thehandle 6. A helical spring 36 surrounds the shaft- 7, one end beingsecured to the base 4 and the other end to the arm 9. y

An electromagnet core 37 is energizedfby a coil 38 to operate anarmature member 39, against the force of a spring 40. A notch 41 is cutin one end of the armature member 39, and a paWl is pressed against theratchet wheel 34 by a spring 43. Armature 39 and pawl 42 are connectedby a rod 44 around which the spring 43 is coiled. Pavel 42 is directlyconnected to the handle 6 by the ratchet Wheel 34. and a sleeve 45 thatconstitutes an extension of handle 6 but is free. from the shaft 7.

Coil .38 has a compensating tap 47 which serves to reduce the number ofturns of the coilivhich are effect-ive on the overload mechanism duringthe starting operation of the motorat which time the current value ishigh. When full motor speed is reached and the current is reduced, thenumber of effective turns in the coil is automatically increased.

In the starting operation of my switch` the handle 6 is turned in acounter-clockwise direction to cause the ratchet-andpawi mechanism 35,35EL to turn the shaft 7 in the same direction.

Contacts 15-18 and 16-19, controlling the starting circuits, are alreadyheld in closed positions by spring 36, The movement of crank 8 causes anelongation and tensioning of spring 12. As crank 8 turns over, itstrikes the end of lever 31, which depresses piston 32 of dash pot 33,allowing the crank 8 to pass by the end of lever 31. When the crankportion 8 reaches its dead-center position with reference to the arm 11,the spring 12 is at a maximum tension. A slight movement beyond thedead-center position permits Y the spring 12 to contract, by a sharpmovement of the crank into contact with the notch 41, to actuate the arm11 and its movable contact members 24 and 25 into Contact withstationary contact members 26 and 27. The electrical connections arethen as shown in Fig. 6.

The movement of the arm 11 causes spring 28 to be placed under tensionto exert'a pulling force upon arm 9 in opposition to the latch 29. Atthe end of a period, corresponding to the time interval required for themotor 1 to reach its running speed,`the dash pot 33 causes its piston 32to lift the lever 31 which bears against latch 29 and thus overcome theforce exerted by the spring 30, thereby releasing arm 9. The lattersnaps into the position for effecting engagement of contact members 14and 17, as is shown in Fig. 7, simultaneously tensioning spring 36.

If an overload exists in the motor supply circuit 2, the electromagnet37'-38 is energized to a degree at which the force of spring 40 isovercome, and armature member 39 is drawn downwardly thereby releasingthe crank portion 8 from the notch 41. Spring 12 then draws the crank-portion 8 and the arm 11 into the starting relation, and spring 3Gactuates arms 9 and, 11 and crank portion 8 of shaft 7 into the foffposition, as shown in Figs. 4 and 5.

It is to be observed that, by the assembly of pawl-and-ratchet mechanism35, 35, sleeve 45 and ratchet wheel 34, with relation to handle 6,movement of shaft 7 in a forward or counter-clockwise direction is nottransmitted to the handle 6. This construction provides a trip-freeattachment for the switch, even though the operators hand is still onthe switch handle.

In order to stop the motor, a clockwise impulse is given handle 6 whichis imparted by sleeve 45, ratchet 34, pawl 42 and rod 44 to armaturemember 39. As shown in Fig. 4, the movement just mentioned releases thecrank member 8 from notch 41, allowing the switch to snap into its ofi7position. Spring 43 maintains the pawl 42 in engagement with the ratchetwheel 34.

It is apparent that I have devised a starting switch of the snap typewhich is characterized by a unidirectional movement of a crank sectionof a shaft or pivot member whereby a trip-free mechanism is obtained.

My invention is not limited to the specific structure illustrated, as itmay be variously modified without departing from the spirit and scope ofthe invention, as set forth in the appended claims.

I claim as my invention:

1. In a switch, a shaft having a crank mounted thereon, a handle on saidshaft, means for imparting a turning movement to said shaft uponmovement of said handle in a single direction, and means for impartingmovement to the shaft in the same direction upon movement of the handlein an opposite direction.

2. In a switch, a shaft, a crank formed on said shaft, a handle on saidshaft, means for imparting a turning movement to said shaft uponmovement of said handle in one direction, means for imparting movementto the shaft in the same direction upon movement of the handle in anopposite direction, and circuit-controlling means associated with saidcrank.

3. In a switch, a shaft, a crank mounted on said shaft, 'meansassociated with said crank for controlling an electrical circuit, ahandle mounted on said shaft, and means comprising an electro-magnet, anarmature cooperating with said electro-magnet, a pawl mounted on saidarmature, and a ratchet attached to said handle for releasing said crankfrom said handle upon the occurrence of overload conditions in saidelectrical circuit.

4. In a switch, a shaft, a crank mounted on said shaft, a handle mountedon said shaft, a ratchet mounted on said sha-ft, a pawl mounted on saidhandle to co-operate with said ratchet, a ratchet mounted on saidhandle,-and means connecting the last named ratchet with said crankwhereby said shaft may be actuated by said handle or said shaft mayope-rate independently of said handle.

5. In a switch, a shaft, a crank mounted on said shaft, a handle mountedon said shaft, a ratchet mounted on said shaft, a pawl mounted on saidhandle to co-operate with said ratchet, a ratchet mounted on saidhandle, and means connecting the last named ratchet with said crankwhereby said shaft may be actuated by said handle or said shaft mayoperate independently of said handle, and an electromagnet for effectingsaid independent movement under conditions of overload.

6. Switch mechanism comprising a pair of relatively movable switchmembers, yielding means for normally holding one switch member in closedposition and the other in open position, and having a portion forbiasing the first switch member toward a second closed position when thesecond switch member is in closed position, means for releasablyretaining the first switch member in closed position and means formoving the second switch member to closed position.

7. Switch mechanism comprising a pair of relatively movable switchmembers, yielding means for normally holding one switch member in closedposition and the other in open position, and having a portion forbiasing the first switch member toward a second closed ition when thesecond switch mem- \ber is 1n closed position, automatically-actu switchmember in closed position and means for moving the second switch memberto closed position.

8. Switch mechanism comprising a. pair of relatively movable #switchmembers, yielding means for normally holding oneswitch mem'- ber inclosed position and the other in open position, and having a portion forbiasing the first switch member toward a second closed position when thesecond switch member is in closed position, time control means forrelcasably retaining the first switch member in closed position andmeans for moving the second switch member to closed position.

9. Switch mechanism comprising a pair of relatively movable switchmembers. means for normally biasing one of the members toward closedposition, means for releasably retaining the said switch member inclosed position, means for closing the other switch member, and ayielding means connecting the Switch members whereby the first switchmember is moved to a second closed position against the action of thesaid biasing means when the second switch member is in closed positionVand after the first switch member is released from its first closedposition.

10. Switch mechanism comprising a pair of relatively movable'switchmembers, means forl normally biasing one of the members towardclosedposition, means for releasably retaining the said switch member inclosed position, means for closing the other switch member, a yieldingmeans connecting the switch members whereby the first switch member ismoved to a second closed position against the action of the said biasingmeans when the second switch member is in closed position and after thefirst switch member is released, and automatically-actuated means forreleasing the first switch member.

11. Switch mechanism comprising a pair of relatively movable switchmembers, one of which is alternately movable into engagement withseparate contact members, and the other into and out of engagement -witha third contact member, yieldmg means for normally holding the firstswitch member in engagement with one ofthe first said contact membersand the second switch member out of engagement with the third contactmember, and having a portion for biasing the first switch member towardthe other of the first contact members when the second switch member isclosed, means for releasably retaining the first switch member in itsinitial position and means for moving the second switch member to closedposition.

ated means for releasa-blyretaining the first 12. Switch mechanismcomprising a. rotatable unidirectional operating shaft, a Switch membermovable to open and to closed positions in response to rotary movementof the operating shaft, means for arresting move- .ment of the operatingshaft when the switch member has moved to closed position, an operatinghandle for rotating the shaft, means for connecting the shaft and thehandle whereby rotation of the shaft is permitted independently of thehandle and irrespective of the position of the handle, and meansactuated by the handle when turned in the direction opposite to that inwhich the shaft rotates for releasing the shaft-arresting means topermit opening movement of the switch member.

14. Switch mechanism comprising a rotatable unidirectional operatingshaft, a switch member movable to open and to closed positions inresponse to rotary movement of theV operating shaft, .means forarresting movement of the operating shaft when the switch member hasmoved to closed position, an operating handle for rotating the shaft andmeans responsive to current conditions and also actuated by the handlewhen the latter is turned in the direction opposite to that in ,whichthe shaft rotates for releasing the shaft-arresting means to permitopening movement of the switch member.

15. In a switch mechanism, the combination with a rotatableunidirectional operating shaft, and a pivotally mounted switch member,of an overcenter spring connecting the switch member and shaft formoving the switch member to closed position in response to apredetermined movement of the shaft,

means for arresting movement of the shaft aft/er the switch is closed,and yielding means tensioned by closing movement of the switch memberfor moving the switch to open position when the shaft has been released.

16. In a switch mechanism, the combination with a rotatableunidirectional operatincluding a second switch member tensioned to openposition by closing movement of the first switch member for moving thefirst switch member to open position, and the second switch member toclosed position when the shaft is released.

17. In a switch mechanism, the combination with a rotatableunidirectional operating shaft, and a pivotally mounted switch member,of an overcenter spring connecting the switch member and shaft formoving the switch member to closed position in response to apredetermined movement of the shaft, means for arresting movement of theshaft after the switch member isl closed, yielding means including asecond switch member tensioned by closmg movement of the switch memberfor moving theswitch member to open position when the shaft has been re#leased, timecontrolled means for releasing the second switch member forpermitting opening movement thereof, and a current-responsive meansforreleasing the operating shaft.

18. In a switch mechanism, the combination with a rotatableunidirectional operat- Aing shaft, and a pivotally mounted switchmember, of an overcenter s ring connecting the lswitch member andshafifl for moving the switch member to closed position in response to apredetermined movement of the shaft, means for arresting movement of theshaft after the switch is closed, yielding means including a secondswitch member tensioned by closing movement of the switch member for'moving the switch member to open position when the shaft hasI beenreleased, and separate automatically-actuated means for releasing thesecond switch member for permitting opening movement thereof and forrreleasing the'operating shaft.

19. A motor-starting switch comprising a running switch, a startingswitch, an electromagnet for controlling the running switch and providedwith a magnetic coil having a portion only thereof connected in therunning switch circuit when the starting switch is closed and means forconnecting additional coils in the running switch circuit when thestarting switch is open.

20. A motor-starting switch comprising a running switch, a startingswitch, an electromagnet for controlling the running switch and providedwith a magnetic coil having a portion thereof connected in the runningswitch circuit when the starting switch is closed and means forconnecting another por-- tion in the running switch circuit when thestarting switch is open.

21. A motor-starting switch comprising a running switch, a startingswitch, an electromagnet for controlling the running switch connected inthe running switch circuit and means for rendering the electromagnet.operative at lower current values when the sta-rt ing switch is open.

22. Switch mechanism comprising a pair of switch members, movable inopposite directions to close their respective circuits, a unidirectionaloperating shaft, means for connecting the shaft with one of the switchmembers whereby movement of the shaft causes alternate opening andclosing movements thereof, means for normally yieldingly retaining theother switch in closed position, means for releasably latching theswitch member in closed position, means actuated by the first switchmember for biasing the second switch member toward open position againstthe action of the said yielding means and time control means forlreleasing the second switch member.

In testimony whereof, I have hereunto subscribed my name this seventhday of February 1923.

HAROLD G. BAXTER.

